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    Mike Jonas, Can you tell me where Patrick Moore got the 15,000 Gt C in the atmosphere 500 Ma ago? <blockquote>Today, at just over 400 ppm, there are 850 billion tons of carbon as CO2 in the atmosphere. By comparison, when modern life-forms evolved over 500 million years ago there was nearly 15,000 billion tons of carbon in the atmosphere, 17 times today’s level. </blockquote> The 15,000 Gt C doesn't seem right to me. The Ediacarans were the first complex animal life and the first that could move. They began during the last snowball Earth period, about 620 Ma. This was colder than present, so CO2 concentrations would have been less than in the much warmer Cambrian period that followed. During the Cambrian explosion (of life), CO2 concentrations were around 2000 ppm, i.e. about 5 times higher than present. This seems at odds with the "17 times today's level" quoted from Patrick Moore.

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    Why do you say that was 10,000 BC? It's title is "Coastlines of the Ice age". Should that be around 20,000 years ago, rather than 10,000 BC?

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    <blockquote>A check on the sea levels over the past several glacial cycles (500ka) given in the ref) shows that sea levels actually do stop at around 0 and 120m. The warming and cooling are processes that are based on the Milankovitch cycles, but with feedback mechanisms that stop the process at the stated levels.</blockquote> No sir, according to Spratt et al., 2016 the drop in sea levels: https://i.imgur.com/hoX5vpR.png At 24 kyr BP stopped at –130 At 135 kyr BP stopped at –124 At 250 kyr BP stopped at –90 At 340 kyr BP stopped at -100 At 425 kyr BP stopped at –124 At 540 kyr BP stopped at –67 At 630 kyr BP stopped at –115 At 720 kyr BP stopped at –90 So only in two cases sea levels stopped at –120 m below current sea level. Four cases if –120 ± 10. Still another four cases between 20-50 m above that supposed target. It seems to me that the premise with which you start your article is not correct, regardless of what your reference says. There are no fixed levels. Melting and freezing proceed until they can't for a variety of reasons, mainly due to Milankovitch orbital changes.

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    I'm a bit skeptical about all global warming and cooling being related to changes in CO2 uptake and outgassing on the vast periphery the continents as sea level rises and falls on millennial timescales. Where does changes in solar activity enter the equation?

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    I didn't mean the above was from 10,000 BC. It would nice if I could find one from 18,000 BC from a good source.

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    Judith, I wondered if this was worth putting up as a post on Arctic Sea Ice. Might need some editing. Perhaps others here could take it and redraft it into something respectable without my bias. Sincerely angech Yo yo ice, probability and natural variation.. While everyone has been focusing on CO2 and MGST a funny thing has been happening [at the forum] with the sea ice extents this last 8 months. Which should cause some scratching of heads and readjustments in the range we currently give to natural variability, in our assessment of the causes of sea ice growth and the reliability of Arctic and Antarctic temperature recording. 2018 had the lowest winter maximum extent of the last 40 years of the satellite record despite a promising early regrowth. As such it was expected that it could set a new low record for the minimum summer extent comparable to that of 2016. Arctic temperatures fluctuated much higher than average though possibly on a par with the last 4 years during the melting season. Robust claims were made but the ice stubbornly refused to play along. Arctic hurricanes and large sea swells were predicted to break it up very quickly but the ice stubbornly sat there melting very slowly on top of an even more unexpected slow volume loss. Consequently when the minimum arrived despite the heroic high temperatures it had gone from the lowest maximum extent to the 8th lowest minimum in September. Skeptics were crowing and then it refused to refreeze dropping rapidly to the second lowest recovering extent in October. Then weirdness set in with pockets of quick refreeze in November in areas, Barents and Chukchi, which were sadly lacking the previous year. The East Siberian Sea, stalwart in not melting early but a long slow late melt refroze overnight [well not quite but rapidly]. The Hudson Bay started to freeze and November offered up an impossible freezing sequence of 16 days of way well above average freezing rates despite the high temperatures. From 2nd lowest to 13th or 14th lowest in that time. Unprecedented, alarming freezing. The trend went from below 2010 to equal to the 2010 average and then, almost, to the 2000 average in that 16 days. Why? Silence. As suddenly as it did the freeze it stopped. 2 weeks of below par freezing brought it back to the 2nd lowest. Then two human comedies. NASA mucked up with a graph on incomplete data that showed an impossible regrowth day that took 3 days to correct. Finally the last week into December. Ice growth recouped again helped by a shuffle at the end of December where growth rates are reset by the algorithms they use which give a jump to reflect an offset that develops each month [Masking]. Currently we sit in 8th place with a steep rise occurring and looking likely to continue. What is to like? A recovery of sorts from the warm weather and currents stimulated by the 2016 El Nino and the 2017 rewarmth has occurred as expected due to the warming lag in these events finally wearing off. Further melting rate increase might occur in 4 months when the 2018 baby El Nino currents again reach the Arctic. This recovery might be big enough to give all concerned pause for thought as to how we should be assessing Arctic variability. What is not to like? When 16 days can give a fluctuation that should normally take 10 or more years to develop without due cause [unpredicted, unprecedented] The problem is not with the fluctuations but the concept of how much natural variation is actually capable of occurring. These results strongly suggest that variability in the Arctic is much greater than the trends of the last 40 years predict. The take home message is good for both sides. The last 10 years of data show a slowdown or pause in melting which might be the bottom of a cycle that is going to turn upwards if we choose to believe in 60 yar cycles. For warmists the fact that such large fluctuations can exist [independent of CO2 and surface temperatures] means there is also an outside chance of further large downward fluctuations. JAXA ARCTIC EXTENT 6,731,603 km2?October 24, 2018?- Extent is lowest in the satellite record- Extent increase at 156 k is about 55 k ABOVE the average (2008-2017) on this day, JAXA ARCTIC EXTENT 6,933,069 km2? October 25, 2018?- Extent is 2nd lowest in the satellite record, - Extent increase at 201 k is about 110 k ABOVE the average (2008-2017) on this JAXA ARCTIC EXTENT 7,182,053 km2? October 26, 2018?- Extent is 3rd lowest in the satellite record, - Extent increase at 249 k is nearly 160 k ABOVE the average (2008-2017) on this day, JAXA ARCTIC EXTENT 8,624,638 km2?November 5, 2018?- Extent is 4th lowest in the satellite record, JAXA ARCTIC EXTENT 9,278,237 km2?November 14, 2018?- Extent is 6th lowest in the satellite record, JAXA ARCTIC EXTENT 10,272,807 km2?November 22, 2018?– Extent is 13th lowest in the satellite record. JAXA ARCTIC EXTENT 11,197,247 km2?December 11, 2018?- Extent is 2nd lowest (JAXA)] ASI Extent. December 16th, 2018: [The error] 11,752,725 km2, an increase of 263,728 km2. 2018 is now the 9th lowest on record. JAXA ARCTIC EXTENT 11,752,393 km2? December 22, 2018? - Extent is 4th lowest JAXA ARCTIC EXTENT 11,871,945 km2? December 28, 2018? - Extent is 2nd lowest JAXA ARCTIC EXTENT 12,590,152 km2 ?January 4, 2019 - Extent is 8th lowest [figures from others posting at Arctic Sea Ice Forum] * not a member

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    ta

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    It's hard to regard with a high interval of confidence a source who has as high an interval of confidencein the Trump administration's scientific bona fides that which Judith displayed in running Patrick Michaels' 'National Climate Assessment and the Trump administration The National Climate Assessment must be redirected or terminated' eighteen months and a half dozen cabinet members ago.

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    What an irrelevant and totally unscientific comment Russell.

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    https://i.imgur.com/SIsjPWO.png https://i.imgur.com/KbY6Kjd.png

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    https://i.imgur.com/SIsjPWO.png https://i.imgur.com/KbY6Kjd.png

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    Allan Cannell <blockquote>Re Carbon budget This is difficult to follow – what is easier to check is the measurement of changes in carbon in forests. Burning thousands of ha of the Amazon, replanting tropical rainforest, etc. What seems to have been overlooked in the vast amount of carbon put into the atmosphere by the drowing (in just a few thousand years) of these forests. The ball park figures show that this was significant and lags sea-level rise. This offers an explanation for the “lag” in CO2 re T. </blockquote> By “difficult to follow” do you mean my comment is not clear, or that there is a lack of information on carbon content in the biosphere during earlier geologic periods? The burning of forests is mostly due to humans so is very recent – i.e. most has occurred during the last few centuries, and probably very little prior to the Holocene. The Pleistocene ice ages occurred before that, so the burning does not explain the lag in CO2 re T. The lag in CO2 re T occurred through all the Pleistocene glacial cycles. Further, plotting temperature from Scotese (2018) [1] against CO2 concentration from Foster et al (2017) [2] suggests the lags occurred throughout the Phanerozoic Eon, however, this might be due to the two studies using different dates. [1] Scotese (2018) https://www.researchgate.net/publication/324017003_Phanerozoic_Temperatures_Tropical_Mean_Annual_Temperature_TMAT_Polar_Mean_Annual_Temperature_PMAT_and_Global_Mean_Annual_Temperature_GMAT_for_the_last_540_million_years [2] Foster et al (2017) https://www.nature.com/articles/ncomms14845#f1 I'll add a separate, longer comment at the end of the current thread regarding my interests in the mass of carbon tied up in the biosphere and its implications. I'd welcome your thoughts on it.

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    Allan Cannell, Re: mass of carbon tied up in the biosphere: My interest in the mass of carbon tied up in the biosphere at different time in the geological past is what can be deduced about the impact of global warming on the biosphere. Several lines of evidence seem to suggest that global warming from the current icehouse conditions would be overall beneficial for the biosphere. <b>First</b>, IPCC AR4 WG1 Chapter 6 says: • 10% – 33% less terrestrial carbon storage at the LGM compared to today (300-1000 GtC less C in biosphere at GCM compared with preindustrial 3000 GtC) https://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch6s6-4-1-4.html . That is, the mass of carbon in the biosphere has increased by a factor of 10% to 50% since the last glacial maximum. • “Lower continental aridity during the Mid-Pliocene” https://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch6s6-3-2.html <b>Second</b>, Gillman et al. (2015) <i>Latitude, productivity and species richness</i>’ https://onlinelibrary.wiley.com/doi/pdf/10.1111/geb.12245 “<i>found strong support for a negative relationship between latitude and annual </i>[Net primary productivity]<i> NPP of forests with all datasets, and NPP was significantly greater in tropical forests than in temperate forests. Vascular plant richness was positively correlated with NPP.</i>” They find that “<i>... annual NPP of forests with all datasets, and NPP was significantly greater in tropical forests than in temperate forests. Vascular plant richness was positively correlated with NPP.</i>” They conclude “<i>NPP of forests increases towards the equator. Given that species richness also increases towards the equator, and that vascular plant richness correlates with NPP, these results are consistent with recent meta-analyses showing that the relationships between productivity and species richness of both plants and animals in natural ecosystems are predominantly positive.</i>” <b>Third</b>, the benefits of a warmer planet for life are shown by the period from Eocene Thermal Maximum (50 Ma ago) to Present. Life thrived during warm and warming periods but struggled during cold and cooling periods. Mass extinctions were during cooling periods, not warming. Regarding the Eocene flora https://en.wikipedia.org/wiki/Eocene : “<i>At the beginning of the Eocene, the high temperatures (GMST 26.5 C, tropics 32 C) and warm oceans created a moist, balmy environment, with forests spreading throughout the Earth from pole to pole. Apart from the driest deserts, Earth must have been entirely covered in forests. Polar forests were quite extensive. Fossils and even preserved remains of trees such as swamp cypress and dawn redwood from the Eocene have been found on Ellesmere Island in the Arctic. Even at that time, Ellesmere Island was only a few degrees in latitude further south than it is today. Fossils of subtropical and even tropical trees and plants from the Eocene also have been found in Greenland and Alaska. Tropical rainforests grew as far north as northern North America and Europe. Palm trees were growing as far north as Alaska and northern Europe during the early Eocene, although they became less abundant as the climate cooled. Dawn redwoods were far more extensive as well. </i>” “The end of the Eocene was marked by the Eocene–Oligocene extinction event.” It was a cooling event.

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    Javier The point made is that sea levels drop to around -120 m - but not further - and rise to 0 - but not higher. The data set from the Red Sea gives more consistent values. These constraints fit the current topography and follow the simple equation. If cooling stops the cut-off is not reached. Evaporation over tropical and sub tropical seas (where evaporation is highest) seems to be the main factor. Like most engineers, I like something simple that works and fits the data. Peter "Hard to follow" means hard to figure out where all the C is stacked. I go no further than to estimate the mass of CO2 from ppm data and then add the new carbon stock from drowned forests. My interest in this started (as a plaeoanthropologist) in relation to human migration in the Holocene. Newly exposed beaches would be natural pathways, drowned tangled forests a nasty trek. Carbon from drowned forests has been overlooked and/or downplayed and may be a hot topic for the coming decades. To give an idea: at low sea-levels the western Malvinas cold current (from the Antartica) would be greatly reduced (by about 80%), so the exposed Atlantic Argentine Continental Shelf would have been warmer and less steppe like & MAY have been wooded (those giant sloths browsed on a lot of greens). This area is huge at about 500k km^2 and did not enter into the drowned forest carbon estimate - nor did other temperate forests.. The Early Triassic was cold for about 500 ka, my own take on this being a loss in patm at the end of the Kiaman superchron. For those interested may I suggest the Overview: Giant Bugs, Martian Air Ice Ages etc. Version 7 on my Researchgate page. The JEB paper on the Engineering of Giant Dragonflies (also on the RG page) is an attempt to quantify patm in the Permian from fossil biology - I get about 1.6 bar.

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    A lot of what is in this post is simply wrong, and most of the rest irrelevant. Atmospheric pressure does NOT fall significantly when land supported ice accumulates; land supported ice mostly displaces the atmosphere (very little air is sequestered in the ice), and atmospheric pressure at the ocean surface rises by approximately the equivalent of ~120 meters of altitude if sea level is 120 meters lower. If we use the ‘standard atmosphere’ lapse rate of ~6.5C per KM, that is equivalent to a 0.78 C increase in ocean surface air temperature (all else equal). All that low altitude exposed land will also have more atmosphere above it for the same reason... and be a little warmer than it would otherwise be.

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    Hi Steve Yep, patm at sea level is pretty much the same; a bit less for the air lost in ice, a bit less from the lower water vapour. The point being made is that for PRESENT land, the equivalent loss in patm is all the above PLUS the new height. So in Curitiba (where I live at 940 m above sea-level, during the LGM the house would be 1060 m plus the effect of the lesser patm.

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    <blockquote>The point made is that sea levels drop to around -120 m – but not further</blockquote> Alan, the point has not been made. How do you know that the stopping of the cooling is not responsible for the stopping of the sea-level drop? We know that the cooling causes the sea-level drop, as it starts earlier. To make your point you would need a period of significant cooling after reaching -120 m when there is no further sea-level drop, showing that there is a temperature-independent limit. Good luck finding it.

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    "Low solar activity has a disproportionate effect on climate, much larger than high solar activity. " The F10.7cm solar radio flux data indicates 57.1% of days since 1947 were below my solar flux ocean warming threshold of 120 sfu, during the top cycles of the modern maximum in solar activity. 2/1/1947 to now SF>120 11,259 42.9% SF<120 14,994 57.1% When you look further back with v2 SSN as I did in <a href="https://www.dropbox.com/s/6u77dn0ud15qglk/AGU%20Fig16.JPG?dl=0" rel="nofollow">Fig. 16</a> of my poster, you can see there were times since 1818 during lower solar activity associated with cooling, when there was a larger disparity between the sum of zero sunspots days versus the overall sunspot number average as compared to modern maximum years. If we had F10.7cm data since 1818 the number of SF days <120 sfu would've fluctuated to a higher percentage. Using this as a guiding principle, when we look even further back in time to cold epochs and ice ages, it doesn't take much imagination to envision long periods of low activity where the percentage of days under the warming threshold nears 100%, explaining the source of the cold, like the Maunder Minimum. The key factor is <i><b>duration</b> under TSI extremes</i>. The sun controls the ocean, which controls the atmosphere, in that order.

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    I assume that the direct effect on air pressure on land of a 120 m lower sea level is small. Transforming 120 m water to ice increases volume by SE * 0.7 * 120 * (1/0.917 - 1)= SE * 7.6 m, so air pressure increases by ~8 m (SE= surface of the Earth). However, the density of the air displaced by the ice is lower than that of the air above the lower sea level. Assuming an increase in height of 1 km for an average water/ice particle, this effect results in an 11 m lower air pressure. The net result would be a 3 m lower air pressure on land and a 117 m higher air pressure at sea level, from which the other effects of 20 m (air sequestration) + 10 m (glacial deformation) + 45 m (loss of gaseous water) have to be subtracted.

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    Meu amigo, você está totalmente enganado sobre isso. The density of glacial ice is lower than water (~0.917 g/ml at depths >200 meters) so the loss of volume of "sequestered air" is almost perfectly compensated for by the greater volume of ice versus the same mass of water. As the ice sheet builds, the loss of ocean volume is almost identical to the increase in volume of ice... which displaces the atmosphere where ice sheets form..... meaning that at a fixed altitude (relative to the Earth's center, not relative to sea level), there would be no significant change in atmospheric pressure. So unless Curitiba changed altitude significantly due to isostatic adjustment (I doubt this... glaciers were pretty far away: https://en.wikipedia.org/wiki/Last_Glacial_Maximum#/media/File:CLIMAP.jpg), the atmospheric pressure at ground level would be virtually unchanged during the last ice age versus today. Note in the map linked above that the ocean surface temperature in much of the Pacific was *WARMER* than today (temperature estimate based on analysis of ocean sediment). This is consistent with HIGHER atmospheric pressure over the Pacific, not lower.

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